There’s not much traffic in Merida except mid-afternoon school pick-up time.  If you encounter traffic at other times it is usually due to:

-horse-drawn carriage

-somebody trying to buy mangoes, newspapers, or phone cards from the street vendors without correct change

-police check point

-unbelievably dilapidated car unable to surpass 10k/hr

-bizarre advertising event, such as a giant Modelo beer on giant ice cubes flanked by guys in matching overalls on motorcycles…